THE PILOT STATED HE WAS TO MAKE HIS FIRST PASS FROM SOUTH TO NORTH OVER A SET OF POWER LINES THAT HE WAS AWARE OF ON THE SOUTH END OF THE FIELD. HE INITIATED THE PASS BY DIVING INTO THE FIELD OVER THE LINES. AS HE DID SO, HE SAW A SECOND SET OF 30 FOOT HIGH LINES, 291 FEET NORTH OF THE FIRST. HE SUCCESSFULLY WENT UNDER THE SECOND LINES; HOWEVER, THE AIRPLANE STRUCK THE GROUND SHORTLY THEREAFTER. THE SUPPORT POLES FOR THE SECOND SET OF LINES WERE OBSCURED.